<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>

		<script src="https://unpkg.com/vue@3/dist/vue.global.js"></script>
	</head>
	<body>
		<div id="app">
			{{num}}
			<br />
			<input type="text" v-model="num" />
			<br />
			{{message}}
		</div>
		
		<script>
			var app = Vue.createApp({
				data() {
					return {
						"message": "Hello Vue!",
						"num":10
					}
				},
				// 数据的监听
				watch:{
					num(newVal,oldVal){
						console.log("旧的值"+oldVal)
						console.log("新的值"+newVal)
						this.message = "监听到num数据改变了，旧的值"+oldVal+"新的值"+newVal
					}
				}
				
			});
			var vm = app.mount("#app")
		</script>



	</body>
</html>